There are two kinds of reading in Northanger Abbey: reading books and letters, and reading people. Catherine Morland is young and naïve, and she has a hard time distinguishing between the two types of reading. Before Catherine can really enter the world of adulthood, she needs to improve her ability to read people as well as novels. Throughout Northanger Abbey, Catherine finds herself unable to "read between the lines." She does not notice the obvious romance developing between James and Isabella, she does not understand why Frederick Tilney gets involved, she has no idea why the General is so kind to her. All of these behaviors and motivations are clear to the reader and to the characters surrounding Catherine. When Catherine finally tries to do some of her own analysis, she gets her perceptions mixed up with those encouraged by her novel-reading: she recognizes General Tilney's grumpiness and the tyrannical control he tries to exert over his children, but she attributes his attitude to the grisly murder of his wife, since such a plot twist occurs frequently in Gothic novels.
One defining moment for Catherine comes as a result of reading text. She receives a letter from Isabella, and its contents open Catherine's eyes to Isabella's manipulative, ambitious ways. It would be going a bit too far to say that Catherine is an expert at reading people by the end of the novel, but she does become better at it, and she has learned when imagination can aid perception, and when it can hurt it.
In Austen's novels, characters are often partly defined by their wealth and status. In Northanger Abbey, several characters are preoccupied with material longings. Isabella wants to marry someone rich, and forsakes James in favor of the richer Frederick. Mrs. Allen is obsessed with clothing and shopping, and when talking to Mrs. Thorpe, she feels less bad about her own childlessness when she notices the shabbiness of Mrs. Thorpe's clothes. The General wants his children to marry into rich and wealthy families, and his personal obsession is with remodeling and landscaping. While giving a guided tour of Northanger Abbey, the General constantly asks Catherine to compare his home and gardens to those of Mr. Allen, and is always pleased to find that his belongings are larger or more impressive. In her later novels, Austen linked character's personalities with the particular items they loved. In this early novel, she makes wealth itself the goal and passion of characters like Isabella and General Tilney.